Noonan started working in theatre (appearing in the original Off-Broadway production of Sam Shepard's play Buried Child), but in the 1980s he began working in film. At 6 feet, 5 inches (196 cm), Noonan's imposing presence is probably responsible for his tendency to be cast as menacing villains, as in RoboCop 2, Last Action Hero, Manhunter, and The Pledge. His height was used for comic effect in "The Moving Finger," the series finale of the horror anthology Monsters (several episodes of which he also directed and wrote).